Garden ?. how do I keep my mint from taking over my herb garden?

My "over the back fence" neighbor and I both have small mint patches. We use straight vinegar around the perimeter then cover with mulch. For the most part, keeps it in check. For the babies that pop up here and there, we just pluck them out before they spread.

You have several options, containers is the easiest. I have square foot gardens and one has mint and I don't have a problem with it be invasive .

When I set up my raised bed garden I decided to use cinder blocks for the walls (8 blocks long and 4 blocks wide and 2 blocks and 2 blocks high), draped painter's plastic (be sure to punch a few holes every foot for drainage), then put in my compost/fertilizer mixture (including in the holes of the cinder blocks), then the soil. I used the hole part for things that would invade (like mint) or could "fit into small spaces" (other herbs and spices including onions and garlic and individual sunflowers) and flowers that repelled insects. Voila problem solved and it allowed me to use my space wisely to boot.

Agree that containers are the best for mint. There are a few herbs that are very invasive. I use containers for herbs now. I got tired of trying to limit the size of mint and oregano. My oregano would go from a six inch patch to at least two square feet by the end of the Minnesota first freeze and I would cut and dig it back every spring. My mint did the same thing. Hence now all are in containers!

I pinch mine with clips so they grow in a bunch and it works i tried it last year and will be doing it this year as well

I put mine in a old whiskey barrel half and it stays controlled

I have had success with putting the pot in the ground. Put a coffee filter in the bottom of the pot and a layer of gravel over the filter. Add soil and the mint plant. Keep the top of the container higher than soil level and then make sure you cut back the mint plant to keep it from touching the ground around the pot. You really need to be aggressive with preventing mint from touching the soil around the pot because mint roots easily and spreads fast.